A variety of ways have been devised to fasten articles together. For example, it has been proposed to taper the sides of a shaft so that a head portion consisting of, for example, a toothbrush or tool, may be attached, while permitting removal and interchange of the head portion, as disclosed in U.S. Pat. Nos. 1,887,913 (Bell), 3,039,340 (Livermont), 3,182,345 (Smith) and 3,369,265 (Halberstadt et al.). Also, intermeshing joints have been utilized for connecting in woodworking, as disclosed in U.S. Pat. Nos. 1,212,262 (Rockwell), 1,214,261 (Balbach), 1,342,979 (Beitner) and 1,954,242 (Heppenstall), and in metal working, as disclosed in U.S. Pat. Nos. 2,895,753 (Fentiman) and 3,000,658 (Sprouse). Further, inclined or tapered shafts have been utilized for interconnecting the ends of leather washers, as illustrated in U.S. Pat. No. 281,760 (Gingras). However, all of the above have utilized a single shaft and, in some instances, either provided protruding elements along the sides or a T-shaped like-end to provide additional mechanical interference to enhance fastening.
Containers of the type commonly known as "Tupperware" containers (Tupperware is a registered trademark of Kraft, Inc.) and similar containers are disclosed, for example, in U.S. Pat. Nos. 2,487,400 (Tupper), 3,335,774 (Reed), 3,618,802 (Yates, Jr.), 3,730,382 (Heisler), and 3,817,420 (Heisler). The covers of such containers are precisely sized and when mounted, the covers are stretched to cause a tension to be developed in the cover rims between inner and outer retaining lip portions to provide mechanical interlocking for closure. A related patent, U.S. Pat. No. 4,819,309 (Bayemer) discloses that the two parts of a fastener may be identical thereby creating what is referred to as a self-mating fastener.
A number of fasteners utilizing a plurality of longitudinally extending rib and groove elements which deform, mechanically interfere and resiliently interlock with each other have also been disclosed. Examples of such fasteners are described in U.S. Pat. Nos. 2,144,755 (Freedman), 2,558,367 (Madsen), 2,780,261 (Svecedahl), 3,054,434 (Ausnit et al.), 3,173,184 (Ausnit), 3,198,228 (Nato), and 3,633,642 (Segal).
Other fasteners are based on the use of an adhesive. Examples of fasteners that use adhesives as part of the active closure surface are disclosed in U.S. Pat. Nos. 4,699,622 (Toussant et al.), 4,743,242 (Grube et al.), 4,817,816 (Leseman et al.), 4,861,635 (Carpenter et al.), 4,959,265 (Wood et al., 5,158,557 (Noreen et al.) and 5,221,176 (Battrell et al.).
There are also a number of mechanical fasteners based on the interaction of multiple engaging elements. One group of such fasteners includes the hook-to-hook fastener disclosed in U.S. Pat. No. 2,717,437 (Mestral), the hook-to-loop fastener described in U.S. Pat. No. 3,009,235 (Mestral), and the headed stem or mushroom-to-loop fastener disclosed in U.S. Pat. No. 4,846,815 (Scripps).
Another group of related patents describe fasteners which include functional surfaces with patterns of interlocking elements. The interlocking elements have contoured heads in a variety of shapes which fit into cavities between the base or stem of the complimentary functional surface of the fastener. Normally these fasteners are self-mating and often the headed portion of the elements is larger in diameter or a cross section than the space between heads on the complimentary functional surface. Examples of this type of fastener are illustrated in U.S. Pat. Nos. 2,499,898 (Anderson), 3,192,589 (Pearson), 3,266,113 (Flanagan, Jr.), 3,408,705 (Kayser et al.) and 5,097,570 (Gershenson). U.S. Pat. No. 3,899,805, which discloses the use of hollow-headed interacting elements, is a variation of this type of approach. All of these fasteners based on the mechanical interaction of a multiplicity of elements function by fitting an expanded region of an element on one functional surface into a seat or cavity which is a reduced cross-section or restricted pocket on the complementary functional surface. The joining of this type of fastener is normally associated with a single or double snap as the fastener is engaged.
Another type of mechanical fastener that is self-mating and has a multiplicity of intermeshing solid protrusions is disclosed by U.S. Pat. No. 4,875,259 (Appeldorn). Fasteners of the type described in Appeldorn do not make use of interacting elements with expanded heads. Rather, the bond between the complementary functional surfaces of the fastener is due to frictional forces generated between contacting surfaces of the intermeshing protrusions on each of the functional surfaces. The sides of the intermeshing protrusions consist of optically smooth flats. Examples of other fasteners of this type may be found in U.S. Pat. Nos. 5,071,363 (Reylek et al.), 5,088,164 (Wilson et al.), 5,113,555 (Wilson et al.), and 5,201,101 (Rouser et al.).
Yet another self-mating fastener which functions by engaging projections on one functional surface into receptacles on a complementary functional surface to form a releasable friction fit is disclosed in U.S. Pat. No. 4,581,892 (Spier). The projections on one surface perforate a web on the second surface and alternate in rows from one side of the web to the other.
Because of the wide variety of potential applications for fasteners there is a continued demand for new fasteners having enhanced performance with regard to a wide variety of factors, e.g., the number of closures, engagement and disengagement forces, noise, relative movement between fastener surfaces, washability, resistance to soiling or contamination, and the level of load or shear stress the fastener will support. There is a continued need for the development of fasteners having enhanced properties with regard to one or more of these factors that will also satisfy requirements concerning ease of manufacture and constraints on cost.